#include <core.p4>
#include <v1model.p4>

// 定义以太网和 IPv4 头部类型
typedef bit<48> EthernetAddress;
typedef bit<32> IPv4Address;

header ethernet_t {
    EthernetAddress dstAddr;
    EthernetAddress srcAddr;
    bit<16> etherType;
}

header ipv4_t {
    bit<4> version;
    bit<4> ihl;
    bit<8> diffserv;
    bit<16> totalLen;
    bit<16> identification;
    bit<3> flags;
    bit<13> fragOffset;
    bit<8> ttl;
    bit<8> protocol;
    bit<16> hdrChecksum;
    IPv4Address srcAddr;
    IPv4Address dstAddr;
}

struct metadata {
    bit<32> ecmp_select;
}

struct headers {
    ethernet_t ethernet;
    ipv4_t ipv4;
}

parser MyParser(packet_in packet,
                out headers hdr,
                inout metadata meta) {
    state start {
        packet.extract(hdr.ethernet);
        transition select(hdr.ethernet.etherType) {
            0x0800: parse_ipv4;
            default: accept;
        }
    }

    state parse_ipv4 {
        packet.extract(hdr.ipv4);
        transition accept;
    }
}

// 定义 IPv4 转发动作
action ipv4_forward(bit<9> port, EthernetAddress dst_mac, EthernetAddress src_mac) {
    standard_metadata.egress_spec = port;
    hdr.ethernet.dstAddr = dst_mac;
    hdr.ethernet.srcAddr = src_mac;
    hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
}

// 定义 ECMP 选择动作
action set_ecmp_select() {
    meta.ecmp_select = hash(hdr.ipv4.srcAddr, hdr.ipv4.dstAddr, hdr.ipv4.protocol, 
                            standard_metadata.ingress_port, 0, HashAlgorithm.crc32) % 4;
}

// 定义 IPv4 转发表
table ipv4_forward_table {
    key = {
        hdr.ipv4.dstAddr: exact;
    }
    actions = {
        ipv4_forward;
        NoAction;
    }
    size = 1024;
    default_action = NoAction();
}

// 定义 ECMP 组表
table ecmp_group {
    key = {
        hdr.ipv4.dstAddr: exact;
    }
    actions = {
        set_ecmp_select;
        NoAction;
    }
    size = 1024;
    default_action = NoAction();
}

// 定义 ECMP 下一跳表
table ecmp_nhop {
    key = {
        meta.ecmp_select: exact;
    }
    actions = {
        ipv4_forward;
        NoAction;
    }
    size = 1024;
    default_action = NoAction();
}

control MyIngress(inout headers hdr,
                  inout metadata meta,
                  inout standard_metadata_t standard_metadata) {
    if (hdr.ipv4.isValid()) {
        if (hdr.ipv4.dstAddr == 0x0a000001 || hdr.ipv4.dstAddr == 0x0a000002) {
            apply(ecmp_group);
            apply(ecmp_nhop);
        } else {
            apply(ipv4_forward_table);
        }
    }
}

control MyEgress(inout headers hdr,
                 inout metadata meta,
                 inout standard_metadata_t standard_metadata) {
    // 可以添加 egress 控制逻辑
}

control MyDeparser(packet_out packet,
                   in headers hdr) {
    packet.emit(hdr.ethernet);
    if (hdr.ipv4.isValid()) {
        packet.emit(hdr.ipv4);
    }
}

control MyVerifyChecksum(inout headers hdr,
                         inout metadata meta) {
    // 可以添加校验和验证逻辑
}

control MyComputeChecksum(inout headers hdr,
                          inout metadata meta) {
    // 可以添加校验和计算逻辑
}

package MyIngressEgress(MyParser parser,
                        MyVerifyChecksum verify,
                        MyIngress ingress,
                        MyEgress egress,
                        MyComputeChecksum compute,
                        MyDeparser deparser) {
    parser = parser;
    verify_checksum = verify;
    ingress = ingress;
    egress = egress;
    compute_checksum = compute;
    deparser = deparser;
}